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Charlie MasikuDeputy Medical Coordinator
MSF HIV Project, Chiradzulu, Malawi
Capetown 22nd September 2014
Early experience with implementation of
SAMBA HIV viral load testing in a rural district - Malawi
Malawi: rural districtPopulation ~ 300,000, HIV prevalence 17%Chronic lack of health HRProgram very decentralised in 10 HIV clinics + 1 hospital 28 802 patients followed-up on ART (> 80% decentralised)
- Until sept 2013: VL requested only for suspicion of treatment failure - 1.7% only on second line regimen
MSF- MoH Project
SAMBA
Simple AMplification Based Assay
- A Simple Nucleic Acid Testing platform
- Semi-quantitative plasma VL ( ≥ or < 1000 copies/mL)
- Qualitative EID (ongoing field clinical trials) preliminary results in Uganda and Kenya presented at IAS 2014
SAMBA – VL
- Isothermal amplification with simple visual detection
- 300µL of plasma needed
- Preloaded reagents in closed cartridges
- Heat stable freeze-dried reagents
- TAT = 105 minutes
(without centrifugation)
SAMBA I platform
SAMBA prep SAMBA amp
Protocole in use for VL
From date of ART start (defines the milestones)1 VL at M61 VL every 2 yearsAdditional if patient suspect of failure
In addition (MSF)2 VL/yr for children and adolescents2 VL/yr for second line
Definition of failure for ART switch VL > 1000 copies/mL x 3 times In between: reinforcement of adherence counselling
Lessons learned - SAMBA 1 system
Easy to installModerate footprintAll consumables included Short training : lab techs autonomous after 4-5 runs
CHW would need longer training and closer supervisionNb of theoretical runs depend on the nb of equipment and the working hours
Theoretical optimised throughput
1 SP + 1 SA 1 SP + 2 SA 1 SP + 3 SA
Nb tests
Duration Nb tests
Duration Nb tests
Duration
1 run 4 2 h 20 6 2 h 20 6 2 h 20
2 runs 8 3 h 45 8 2 h 50 12 2 h 55
3 runs 12 5 h 15 14 3 h 35 18 4 h 00
4 runs 16 6 h 40 16 3 h 55 24 4 h 35
5 runs 20 8 h 05 22 4 h 40 30 5 h 10
6 runs 24 5 h 10 36 6 h 15
7 runs 30 5 h 55 42 6 h 50
8 runs 32 6 h 25 48 7 h 25
9 runs 38 7 h 10
10 runs 40 7 h 40
Lessons learned – SAMBA 1 system
Volume of the kits : 12 tests = 14 litresWaste to be considered (but no toxic chemicals)Instrument adaptation ongoing
Tolerance above 35°C (room ventilation/insulation)Mechanical problems (blockages) with SAMBA prep
Design of the mobile arm modified on SAMBA prep version 2 Design of the adaptor modifed
Invalid rate extremely low: 6903 samples tested
19 non-repeatable invalid (0.3%) 1 repeatably invalid
Current versus needed VL throughputWith 1 SAMBA prep & 3 SAMBA amp
ART Cohort Q1, 2014
VL Needed /
year(0,66/pat/yr)
Observed current
throughput/day
Estimation VL done in
the HC /year
Difference VL done
vs needed Percent
Hospital cohort 4671 3083 24 6048 + 2965 + 49.0%
HC 1 cohort 4239 2798 8 2016 - 782 - 38.8%
HC 2 cohort 3300 2178 14 3696 + 1518 + 41.1%
With improved patient and sample flow, the observed throughput progresses regularly.
Reaching an optimised throughput
Get the samples to reach the clinic laboratory earlyBlood drawing early, when patients arrive for result/action the
same dayOr VL requested at previous consultation and result/action at
next visitClinicians issues
Train specialised community workers from the villages to perform SAMBA (& other POC?)
No time lost due to lab tech transportation to/from their work place
Operational Research planned on task-shifting to TCW
Breakdown by type of requests
Type of request Number of tests
< 1000 > 1000
6 months ART 197 180 (91.3%) 17
« Routine » ART FU 2915 2588 (88.8%) 327
Suspicion treatment failure (CD4)
824 491 (59.6%) 333
After enhanced adherence counselling
41 24 (58.5%) 17
Other 211 176 (83.4%) 35
Total 4188 3459 729
More straight-forward clinical decision making on treatment strategy than looking at CD4 trends
Reduction of clinic workload / Optimised use of scarce HR
- Spacing of clinical appointments for patients < 1000 copies /mL
- Longer consultation time with experienced staff for more vulnerable patients
Failing patients are recognised on time and switched
Impact of VL on clinical management
SAMBA 2
A whole blood VL semi-quantitative test is being developed (plasma separation included in the preparation cartridge)
In near future, both VL semi-quantitative and EID qualitative test with one platform (only cartridge is different)
- Same day result for EID immediate ART start if positive impact on HIV + infant mortality
SAMBA 1 system is much simpler than currently
available Nucleid Acid Testing technologiesSAMBA 1 cartridge tightly closed prevents
contamination of the environment by ampliconsStaff training requirements for SAMBA 1 is minimal SAMBA 1 can be implemented in lower healthcare
levels such as district hospitals or health centres with
a basic laboratory that has electricity
Conclusion
Recommended